Throughout the development of fiber optic data transmission, it has been known that in order to maximize transmission capabilities of the fiber optic system at locations such as taps and splices, it is essential that joined fibers be properly aligned to reduce transmission loss therebetween. It is also known that proper preparation of the end face of the fiber which is to be connected will reduce transmission loss through that fiber end face. It is highly desirable to prepare a optical fiber end face to have a smooth mirror-type finish thereby providing a greater optical transmission area across the end face. In addition, it is also desirable to provide a fiber end face which is nearly perpendicular to the longitudinal axis of the fiber.
There are many known fiber optic cleaving tools which attempt to provide this nearly perfect flat perpendicular end face. Most of these tools employ a scoring blade which is brought down into contact with the fiber to score or nick the fiber surface. This causes a weak point in the fiber at which the fiber can be separated by applying proper axial tension to the fiber on each side of the scored location. Placing axial tension on one side of the scored location assure a better cleaved surface.
Fiber optic termination tools of this type may take many forms. As disclosed in U.S. Pat. No. 4,229,876, issued Oct. 28, 1980, an optical fiber breaker is disclosed where the fiber is placed in axial tension prior to scoring or nicking the fiber surface. This technique claims to provide a superior fiber end face. However, U.S. Pat. Nos. 4,202,475, issued May 13, 1980 and 4,322,025, issued Mar. 30, 1982, disclose optical fiber cutting tools which score a non-tensioned optical fiber and then provide axial tension on each side of the scored location to effect a cleave. These patents also suggest that this sequence provides a superior optical end face. It is also known to effect severing of the scored fiber by applying axial tension in the form of longitudinal pulling of the fiber on each side of the scored location. A device of this type may be seen in U.S. Pat. No. 4,372,048, issued Feb. 8, 1983, and assigned to the assignee of the present invention.
More recently, development of optical fiber cleaving tools has reached a point where a device is available which both longitudinally pulls and bends the fiber about a scored location to effect the severing thereof. U.S. Pat. No. 4,552,290, assigned to the assignee of the present invention, discloses a tool where, in sequence, the fiber is first scored, then axially offset to effect bending, then longitudinally pulled to effect severing. While a tool of this construction provides a fiber termination end having an end face of desired qualities, the sequential steps of the tool's operation may prove to be slightly cumbersome in field applications. Thus, it is desirable to provide a tool which will provide a suitable termination end face by properly applying techniques of scoring and axially tensioning the fiber, yet will be simple to use and operate in field applications.
A further dichotomy is found in existing optical fiber cleaving tools in that many tools cleave a bare fiber extending from an optical cable and others are constructed to cleave a fiber terminated in an optical connector or ferrule. The later type tool is obviously more advantageous for field applications. Examples of the non-connectorized fiber tools are shown in the above-identified '475 and '025 patents, while the above-identified '876 patent is representative of connectorized fiber cleaving tools. While it is desirable to provide a tool which accommodates connectorized fibers, problems associated with connectorization must be overcome.
A major problem found in tools of this nature, is the ability to cleave the fiber within close proximity to the egressing end of the fiber ferrule. It is even more important to provide a cleaved fiber end face which is at a prescribed constant distance from the end of the egressing end of the ferrule. Variations in the length of the fiber with respect to ferrule end, may be caused by improper insertion of the connector into the cleaving tool or deformation of the ferrule, itself, due to over insertion of the connector into the cleaving tool. It is desirable to provide a fiber optic cleaving tool which will accommodate a fiber in a fiber optic connector and which will align the connector in the tool to provide a constant predetermined fiber termination length over repeated uses.